The present invention relates to an arrangement for handling a mobile telephone subscriber which is administered in at least two different standardized mobile telephone networks with a call number which is common to both of the at least two networks. The invention also relates to methods of procedure when handling the subscriber.
It has long been known in mobile telephony to register the position of a mobile subscriber automatically when the mobile has moved between different mobile telephone networks. This type of automatic mobile registration is called roaming. For instance, it is possible within a GSM system extending over several European countries to use a mobile unit while moving from one country to another, without needing to register the new positions of the mobile manually. When the mobile is switched on after having moved from one place to another, the position of the mobile is registered automatically. Once the position of the mobile has been registered, it is again possible to receive calls and to call other subscribers. A mobile telephone system which includes different subsystems is known, for instance, from International Patent Application WO 89/07380. The system includes a main computer which is able to communicate with different local computers, each of which is located in one of the subsystems. The main computer therewith obtains information as to where mobile units are located in the total system. Calls can be set-up to the mobile units, with the aid of the information contained in the main computer. One serious drawback with present-day techniques, is that automatic updating of the position of a mobile unit after the unit has moved to another location requires the move to be made within the same type of standardized mobile telecommunications system, for instance GSM. It is not possible in present-day techniques to transport information automatically from one type of mobile telecommunications system, for instance GSM, to another type of mobile telecommunications system, for instance the Japanese PDC system. A decisive factor is that different types of mobile telecommunications systems communicate internally through the medium of different types of standardized signalling procedures. A Global System for Mobile communication (GSM) and Personal Digital Cellular (PDC) are examples of mobile telecommunications systems in which roaming within the system is available. Roaming in the GSM system is described in European Digital Cellular Communication System; Network architecture GSM 03.02 and Mobile application part GSM 09.02. Roaming in the PDC system is described in the standard TTC JJ/70.10, Ver 3.